In Ukraine, a Nuclear Plant Held Hostage

In the winter darkness, tracer rounds from Russian armored vehicles streaked past nuclear reactors and high-tension electrical lines. A fire broke out. Shrapnel sprayed a reactor containment vessel.

In the control room of Reactor No. 3, operators were horrified.

“Stop firing at the nuclear facility,” one begged over the station’s loudspeakers. “You are endangering the safety of the entire world.”

The danger at the Zaporizhzhia Nuclear Power Plant — a sprawl of cooling towers, nuclear reactors, machine rooms and radioactive waste storage sites — was actually graver than even those who worked...